Subscriptions

Subscriptions offer real-time connection from the client to the server that allows the client to get immediately informed about events happening server-side

• when a client subscribes to an event, it will hold a steady connection to the server. when this event happens, the server will push that corresponding data to the client Therefore, subscriptions are event-based, acting in response to what just happened.
• We can see this in the subscription nomenclature: commentAdded, paymentMethodAdded
• Unlike queries and mutations that follow a typical “request-response-cycle”, subscriptions represent a stream of data sent over to the client.

You should use subscriptions for the following:

• Small, incremental changes to large objects.
  • Repeatedly polling for a large object is expensive, especially when most of the object's fields rarely change. Instead, you can fetch the object's initial state with a query, and your server can proactively push updates to individual fields as they occur.
• Low-latency, real-time updates.
  • For example, a chat application's client wants to receive new messages as soon as they're available.

subscription {
  newPerson {
    name
    age
  }
}

Whenever a newer mutation is performed that creates a new Person, the server sends the information about this person to the client

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Backlinks

• Graphql Documents